Liquid delivery apparatus

ABSTRACT

A liquid delivery apparatus including a reservoir into which liquid may be introduced to pressurize the reservoir, an outlet for discharging liquid under the pressure in the reservoir, a valve to control passage of liquid from the reservoir to the outlet, a control mechanism controlling operation of the valve, and a way to transmit the pressure in the reservoir to the valve control mechanism. The valve includes an opening, a closure member for closing the opening, and a biasing spring, the arrangement of which being such that the valve is normally held closed under the force of the biasing spring and the pressure of the liquid in the reservoir. The valve control mechanism includes a movable element which is acted on by the pressure in the reservoir and transmits a resultant force to the closure member in a direction to open the valve, wherein the respective effective surface areas of the movable element and the closure member and the force of the biasing spring are chosen such that the closure member is opened when the pressure of the liquid in the reservoir reaches a predetermined level.

This invention relates to a liquid apparatus and two new outletarrangements for such apparatus system.

In order to irrigate farm land with, for instance, a waste liquid suchas water run-off, it is presently known to use a pump to pump the liquidthrough a pipe to a "rain" nozzle. Because of pressure losses over thepipe length, it is necessary to use heavy duty pumps and large bore(75-100 mm) pipes.

Arrangements are known for pressurising a liquid in a vessel, for use,e.g. in domestic or industrial water supply apparatus. One sucharrangement comprises a rigid vessel capable of withstanding a highinternal pressure and an inner, flexible bag. The liquid to bepressurised is pumped into the bag which expands in the vessel andpressurises the air in the vessel as the volume around the bagdecreases. When full operating pressure is reached, the pump is turnedoff and liquid may be discharged from the vessel under pressure, forinstance by a tap.

According to a first aspect of the present invention, there is provideda liquid delivery apparatus comprising:

(i) a liquid reservoir into which a liquid may be introduced via aninlet to pressurise said liquid in the reservoir;

(ii) an outlet via which said liquid may be discharged from thereservoir under the pressure of the liquid in the vessel;

(iii) a valve between the reservoir and the outlet to control passage ofliquid from the reservoir to the outlet, said valve having (a) anopening, (b) a closure member adapted to close the opening, and (c) abiasing means, the arrangement of the components of the valve being suchthat the valve is normally held closed under the force of the biasingmeans and the pressure of the liquid in the reservoir;

(iv) a valve control mechanism for controlling the operation of thevalve in response to the pressure of the liquid in the reservoir; and

(v) a means for transmitting the pressure in the reservoir to the valvecontrol mechanism;

wherein the valve control mechanism comprises a movable element which iscapable of being acted on by the pressure of the liquid in the reservoirand transmitting a resultant force to the closure member of the valve ina direction to open the valve, and wherein the respective effectivesurface areas of the movable element and the closure member and theforce of the biasing means are chosen such that the closure member isopened when the pressure of the liquid in the reservoir reaches apredetermined level.

The apparatus of the present invention enables a small pump andrelatively narrow gauge pipe (e.g. 25-30 mm) to be used in discharging aliquid onto, for example, agricultural land. The pressure of liquid inthe reservoir is used to discharge waste liquid over a large area.

In a preferred embodiment, the system may have a rigid housing and aninner movable wall which subdivides the housing into first and secondchambers, which are separated by the said wall and which are of variablevolume depending upon the position of the said inner movable wall. Thewall should be substantially liquid and gas impermeable. The inner wallmay be rigid or semi-rigid with provision for moving in the housing toadjust the relative volumes of the first and second chambers.Alternatively, the inner wall may be a flexible membrane. The inventionwill be described with particular reference to the embodiment in whichthe inner wall is a flexible membrane. The first chamber on one side ofthe flexible membrane contains a substantially compressible fluid,normally a gas such as air, whilst the other side is the liquidreservoir into which the liquid to be distributed is pumped. As liquidis pumped into the second chamber (or reservoir), the flexible membranewill move permitting the second chamber to expand whilst reducing thevolume of the first chamber and compressing and pressurising the fluid(normally air) in the first chamber. The pressure of the fluid on theone side of the membrane is transmitted (for instance by a simple pipe)to the valve control mechanism for controlling the operation of thevalve. The second chamber on the other side of the membrane representsthe liquid reservoir from which the liquid for distribution isdischarged under pressure. In this embodiment of the present invention,the system may be pre-pressurised by increasing the pressure of thefluid in the first chamber; typically, this will involve compressing theair in the first chamber above atmospheric pressure. An alternative topre-pressurising the fluid (e.g. air) in the first chamber is to allowair to leak (at a controlled rate) into the second chamber together withthe liquid (e.g. water) to be distributed.

The relative volumes of the first and second chambers in the restingstate (i.e. with no pressurisation) may vary from device to device.However, in one preferred embodiment, the flexible membrane may be aflexible bag, for example made of a rubber material or the like, whichoccupies a substantial proportion of the total volume of the rigidhousing. In an alternative embodiment, the volume of the first chamber(i.e. on the valve control side of the apparatus) may be small; in suchan instance, it has been found to be important to utilise the principleof leaking air into the distribution side of the device (i.e. the secondchamber) together with the liquid to be distributed.

The pressure of the liquid in the reservoir may be transmitted to thevalve control mechanism either directly or indirectly. Indirecttransmission of the pressure may, for example, be via the fluid (e.g.air) in the first chamber formed between the flexible membrane and therigid housing of the preferred embodiment described above. In thisexample, the means (v) for transmitting the pressure in the vessel tothe control mechanism may comprise a conduit leading from the firstchamber to the valve control mechanism.

The movable element of the valve control mechanism may preferably be awall element of a pressure chamber which chamber is capable of beingpressurised by the pressure of the liquid in the vessel. Typically, thepressure of the liquid in the vessel is transmitted to the pressurechamber by the compressed fluid (e.g. air) in the first chamber. Thecoupling of the movable wall element to the valve element may, forinstance, be a direct mechanical or hydraulic linkage. For instance, thewall element may be coupled with the closure member by a forcetransmission means such as a shaft which transmits the force exerted onthe movable wall element to the closure member.

The biasing means is preferably a spring such as a compression spring.The spring may be adjustable in force, for example by the use of wedgeswhich slightly increase the compression of the spring.

The liquid may be introduced into the said reservoir by a pump. Theinlet to the reservoir may include a non-return valve to ensure thatliquid may only be pumped into the reservoir, and not leak out of thevessel through the inlet. Provision may be made to permit a small, butcontrolled flow of air into the line supplying liquid to the saidreservoir.

The pressure of the liquid in the reservoir may be transmitted directlyor indirectly to the pressure chamber. Thus, on the valve control side,the conduit from the first chamber may lead directly into the pressurechamber or there may be a further control arrangement between the firstchamber and the valve control mechanism to control the supply ofpressure to the valve control mechanism. Normally, the pressure chamberwill be filled with a fluid such as air.

This further control mechanism referred to may include a first means foradjusting the pressure of the fluid in the pressure chamber when thepressure of the pressure source is at a first predetermined level inorder to move the wall element and transmit a force to the closuremember to open the valve, and also a second means for adjusting thepressure of the fluid in the pressure chamber when the pressure of saidpressure source is at a second predetermined level in order to permitthe wall element to return to its original position and allow the valveto close.

This further control mechanism is particularly suited to controlling theoperation of the valve. The movement of the wall element of the pressurechamber is coupled to the closure member of the valve in order tooperate (i.e. open or close) the valve.

The further control mechanism may comprise a first pressure sensorcapable of sensing when the pressure of the pressure source reaches thefirst predetermined level and opening a valve in a valve passageway topressurise the pressure chamber. In this preferred embodiment, thecontrol mechanism also includes a second pressure sensor for determiningwhen the pressure has fallen to the second predetermined level andopening another valve in a valve passageway to discharge the higherpressure in the pressure chamber.

The control mechanism may also include a further valve in a valvepassageway linked to the pressure chamber and which is controlled bymovement of the moveable wall element. This further valve is arranged toensure that when pressure is released in the pressure chamber and themovable wall element starts to return to its first position under theforce of the biasing means, the pressure in the pressure chamber isallowed to discharge fully. Thus, when the movable wall element movesaway from the first position, a linkage between the wall element and thefurther valve causes the further valve to remain in an open position andensures that the higher pressure in the pressure chamber is equalisedwith that in the pressure source. Once pressure in the pressure sourcestarts to build, however, a non-return valve ensures that this higherpressure in the pressure source does not leak into the pressure chambervia the further valve arrangement. Without this arrangement, thepressure chamber might discharge partially and prevent the movable wallelement returning fully to its first position under the action of thebias.

The arrangement of the present invention enables the valve to be rapidlyopened and closed under control of the pressure in the reservoir.Moreover, the fluid in the pressure source (i.e. the gas or air on thevalve control side of the system) does not escape on operation of thevalve by the valve control mechanism because the pressure chamber andassociated control mechanism (when present) represent a closed system.

The fluid used as the pressure source and associated valve controlmechanism and pressure chamber is preferably a gas, most preferably air.

The apparatus of the present invention is particularly suited fordischarging a waste liquid, although it would of course be capable ofdischarging any liquid, such as a clean liquid.

It is also the case that the apparatus of the present invention could bemodified such that it operates at pressures below atmospheric pressure.This would create a pulsed suction device. The pressurised device wouldrequire modification such that the reservoir could be depressurised,rather than pressurised, and the arrangement would also require changessuch that the valve would be opened when a predetermined level of vacuumin the vessel was reached.

A safety mechanism may be provided in the pressure side of the apparatusof the present invention to detect the rise and fall in pressure as theliquid is firs pressurised in the vessel and then discharged. Electricalcircuitry can be provided which detects the frequency of the pressurerises and falls and compares this with a preset frequency value. Ifthere is a leak or blockage in the system, the rise and fall in pressurewill slow and eventually cease. Once the fall in frequency is detected,it can be arranged that the pump pressurising the liquid in thereservoir is switched off.

The rise and fall (oscillating) of pressure on the pressure side of theapparatus may be coupled to a winch via a bellows motor or other similardevice. This enables the apparatus to be driven. For instance, thevessel and associated parts could be mounted on a wheeled frame and awinch (driven for instance by the bellows motor) employed to winch theapparatus along a cable. A rigid or semi-rigid hose connected to theoutlet for discharge of the liquid could function also as a cable onwhich the apparatus is winched. Alternatively, the hose could be hauledin by the winch with the main part of the apparatus fixed andstationary. This arrangement would allow waste water to be distributedover a larger area.

Where the liquid outlet of the apparatus is fixed with respect to therest of the apparatus the liquid is delivered in a single direction onlyand the entire apparatus needs to be moved for water to be delivered inother directions. It is therefore advantageous for a liquid deliveryapparatus to be able to vary the direction in which it can deliver thefluid.

According to a second aspect of the invention there is provided a liquiddelivery apparatus comprising a liquid reservoir into which a liquid maybe introduced via an inlet and in which the liquid may be pressurizedand an outlet via which the liquid can be discharged from the reservoirunder the pressure of the fluid in the reservoir, wherein the outlet ismovably mounted with respect to the reservoir and means are provided forcausing the outlet to move so that the direction in which the liquid maybe discharged relative to the apparatus can be varied.

The outlet may be rotatably mounted on the apparatus.

The means for causing the outlet to move may be mechanically actuated.Preferably, however, the means are actuated by the discharge of liquidfrom the closed vessel under pressure.

The means for causing the outlet to move may take the form of a strikingmember mounted on the apparatus so as to be able to strike the outletcausing it to move. The striking member may be biased towards or againstthe outlet or it may be biased away from the outlet. In the former casethe striking member must be forced away from its bias and then allowedto return to strike the outlet and cause it to move. In the latter casethe biasing means must be removed to allow the striking member to strikethe outlet and cause it to move. The striking member is preferablypivotally mounted with respect to the outlet.

The means for causing the outlet to move could alternatively take theform of the eccentric mounting of the outlet with respect to thedirection in which the liquid leaves the closed vessel under pressure.The force of the discharging liquid as it is forced to change directionin travelling from the reservoir to and out of the outlet is therebyused to cause the outlet to move.

The apparatus according to the second aspect of the invention could becombined with the system according to the first aspect of the invention.

According to a third aspect of the present invention, there is provideda liquid delivery apparatus comprising a reservoir into which a liquidmay be introduced via an inlet and in which the liquid may bepressurised and an outlet via which the liquid can be discharged fromthe reservoir under the pressure of the liquid in the reservoir, whereinthe outlet comprises a chamber of circular cross-section having an inletfor delivery of fluid from the said reservoir and a plurality ofopenings from which the liquid for distribution may be discharged undergravity.

Preferably, the said inlet is tangentially disposed with respect to thechamber in order to dissipate energy of incoming liquid and enable it to"dribble" under gravity out of the said openings which may be arrangedin one end wall of the chamber.

There may be of the order of 5 to 10 openings in the chamber and eachmay be connected to a pipe for distribution of the fluid under gravity.

This particular arrangement enables fluid to be discharged other thanthrough a high pressure nozzle (which is associated with air-pollution)and also has the advantage that relatively large openings may beemployed, which do not block easily. The apparatus according to thethird aspect of the invention could combined with the apparatus of thefirst and/or second aspects of this invention.

For a better understanding of the present invention, and to show how thesame may be carried into effect, reference will now be made, by way ofexample, to the accompanying drawings in which:

FIG. 1 shows a water distributing apparatus in accordance with the firstaspect of the present invention;

FIG. 2 shows the valve control arrangement of the water distributingapparatus shown in FIG. 1;

FIG. 3 shows, in more detail, the control mechanism of the valve controlarrangement shown in FIG. 2;

FIG. 4 is a schematic view of a safety monitoring circuit useful incontrolling the water distributing apparatus of the present invention;

FIG. 5 illustrates a modified valve closure member;

FIG. 6 illustrates a first embodiment of a rotatable raingun accordingto the second aspect of the invention;

FIG. 7 is an elevational view of a second embodiment of a rotatableraingun in a first position; and

FIG. 8 is a plan view of the embodiment of FIG. 7 in a second position;

FIG. 9 is an alternative arrangement of the water reservoir shown inFIG. 1;

FIGS. 10 and 11 illustrate an alternative distribution outlet;

FIG. 12 shows in elevation a self-propelled form of water-distributionequipment in accordance with the invention; and

FIG. 13 shows a simplified front profile of the equipment shown in FIG.12 omitting the water-distribution and drive components.

The water distributing apparatus 1 shown in FIG. 1 comprises a rigidouter wall 2 capable of containing and withstanding a high internal airpressure, ground engaging legs 4, a flexible membrane or bag 6 and anair control line 8, a valve control arrangement 10, a junction chamber11 and a water discharge line 12 (which may be of any desired length)terminating in a "rain" nozzle 14. Defined between the flexible bag 6and the rigid outer wall 2 is an air space 16. An inlet 11 to theflexible bag 6 is provided, the inlet 11 communicating with an inletpipe 7 in which a one-way valve 9 is fitted.

In FIG. 2, there is shown a valve arrangement 18 comprising a valve seat20 and a valve closure 22 having a sealing ring 23. Associated with theprimary value arrangement 18 is a deflector 24. The control arrangement10 comprises a shaft 26 in a sleeve 27 which links the closure member 22to a movable element 28 which defines a wall of a pressure chamber 30. Acompression spring 32 has a first end 32A which bears on the movablewall element 28 exerting a force on the movable wall element 28downwards in FIG. 2 tending to reduce the volume of chamber 30. Thisforce also tends to close the valve via shaft 26. The compression spring32 has another, second, end 32B which bears against the lower wall 34 ofthe junction chamber 11 in the flow line of waste water from theflexible bag 6 to the discharge pipe 12. This junction chamber 11 issealed with respect to the control arrangement 10.

The control arrangement 10 may comprise a control mechanism 40 which isshown in FIG. 3, although this is not essential. This control mechanism40 controls movement of the movable element 28 in response to thepressure of air in the space 16 (FIG. 1). This air pressure iscommunicated to the control mechanism by pipe line 8 (also see FIG. 1).The control mechanism 40 comprises an air input 42 communicating withpipe 8 and the mechanism has three branch lines 44, 46 and 48 each ofwhich is in controlled communication with the pressure chamber 30.

First branch line 44 comprises a first portion 44a and a second portion44b. These two portions are separated by a pressure valve 50 comprisinga diaphragm 52 and a spring 54 urging the diaphragm 52 into abutmentwith a valve seat 54. In the portion 44b of the branch line 44 there isprovided a first non-return valve 53.

Second branch line 46 includes an adjustable second non-return valve 54having an adjustment means 56.

Third branch line 48 includes a third non-return valve 58 and a spoolvalve arrangement 60. Spool valve arrangement 60 comprises an enlargedpassage 63 and a spool valve element 62 having a sealing ring 64. Thespool valve 60 also includes a stem 64 which links the spool valveelement 62 with the movable wall element 28 (see FIG. 2).

FIG. 4 shows safety circuitry 70 comprising a DC supply 72, a pressureswitch 74, a capacitor 76, a variable delay 78 and a motor circuitbreaker 80.

The modified valve closure member 22a shown in FIG. 5 may replace thevalve control member 22 shown in FIG. 2. This modified closure memberhas an alternative method of holding a sealing O-ring 23a comprising aremovable ring 90 which secures the O-ring 23a in position.

FIG. 6 illustrates a raingun 96 which may be used to replace the nozzle14 at the end of pipe line 12 shown in FIG. 1. The raingun 96 comprisesa barrel 98 which is offset from a pivot 100. As waste water isdischarged through the barrel 98, the raingun 96 is made to rotate byrecoil action; waste liquid is therefore distributed over a wider area.

In FIGS. 7 and 8 there is shown a rotatable raingun in accordance withthe second aspect of the invention. The outlet 701 is in the form of acranked pipe which is rotatably mounted to the rest of the apparatus. Ahammer 702 which acts as the striking member is pivotally mounted viasupport 703 and biased to lie against the outlet 701 by means of spring704 attached to support 703 by means of chain 705. A piston 706 is somounted in the outlet pipe 701 that when fluid is discharged underpressure from the closed vessel (not shown in FIGS. 7 and 8) the pistonis forced outwards causing its piston rod 707 to push against aprojection 708 on support 703. In this way support 703 is caused torotate and hammer 702 is swung out in a circle, in practice to aposition about 270° from its starting position. When the hydraulicpressure on piston 706 is reduced the tension in spring 704 causes thehammer 702 to return to its starting position with force where itstrikes against the outlet pipe 701 causing it to rotate with respect tothe closed vessel such that the fluid is next discharged in a directiondiffering from that in which it was last discharged.

The mode of operation of the water distributing apparatus of the firstaspect of the present invention is best shown by reference to anembodiment of the invention which is somewhat more simple than thatshown in the drawings, i.e. one in which air supply line 8 leadsdirectly to the pressure chamber 30 as shown by broken lines in FIG. 2.Thus, such an embodiment does not include the control mechanism 40.Operation is as follows. At the outset, and before the introduction ofany water through the inlet into the chamber surrounding the deflector24, the only force at work is the compression spring 32 which urges thewall element or diaphragm 28 downwards into its lower position and, viathe action of the shaft 26, causes the valve member 22 to adopt itslower, closed position.

As water is introduced under pressure into the chamber surrounding thedeflector 24 the pressure builds up and the increased pressure acts onthe upper surface of the valve 22 tending to keep that valve closed. Thesame pressure is transmitted via the flexible bag 6 to the airsurrounding the bag 6 and hence through the pipe 8 to the chamber 30. Asthe cross-sectional area of the diaphragm plate 28 exceeds that of thevalve member 22 there is a greater hydrostatic/pneumatic force actingupwards on the underside of the diaphragm 28 than there is actingdownwards on the upper side of the valve member 22; however, the valvemember 22 remains in the lower, closed position until such time as thedifference in force on the diaphragm 28 and the valve member 22 exceedsthe downward force caused by the spring 32 on the upper face of thediaphragm 28.

When this happens the diaphragm 28, shaft 26 and valve member 22 moveupwards so as to open the upper valve, thereby permitting theconsiderable volume of water under great pressure within the flexiblebag to shoot past the deflector 24 to the valve and (as the valve member22 is in the raised position as shown in FIG. 2) enter the junctionchamber 11 and out through the water discharge line 12.

It will be seen, therefore, that the surface areas of the closure member22 and the movable wall element 28 and the force of the spring arecritical and must be chosen to give the correct pressure at which it isdesired for the valve 18 to open. In the present example, the diameterof the valve 22 is about 100 mm, the diameter of the wall element 28 isabout 125 mm, and the force of the spring is about 150 kg. This gives anopening pressure of about 7 bar and a closing pressure of about 3 bar.Once the valve 18 opens, the fluid pressure on the closure member 22 isreleased and the valve 18 will stay open until the pressure in thepressure chamber 30 has dropped sufficiently that the force of thespring 32 will close the valve 18.

Returning to the more sophisticated embodiment including the controlmechanism 40 shown in FIG. 3, the mode of operation is as follows.Initially, (i.e. before priming), the pressure of the air in thepressure chamber 30 is at a low level and the chamber 30 is sealed fromthe air in the air space 16 by the non-return valves 53, 54 and 58 andthe pressure sensor mechanism 50 shown in FIG. 3. The movable wallelement 28 in FIG. 2 is effectively urged by the spring means 32 in adirection which tends to reduce the volume of the chamber 30 in view ofthe low pressure in the chamber 30 and the primary valve 18 is closed.The spool valve arrangement 60 is open with the valve element 62 beingdisplaced upward as shown in FIG. 3. When the pressure in the air space16 reaches a first predetermined level which may be, for example, of theorder of 7 bar, this is usually sufficient to enable the waste liquid tobe sprayed a substantial distance out of the nozzle 14 in FIG. 1. Thepressure sensor arrangement 50 is set to open at this pressure; thus,when the pressure reaches the first predetermined level the air pressureon the diaphragm 52 overcomes the force of the spring 54 therebyenabling portions 44a and 44b of the first branch 44 to be brought intocommunication. The pressure of air in the control mechanism 40 is thensufficient to overcome the closing force of the one way valve 53 andpressurise the chamber 30. Essentially, the pressure chamber 30 ispressurised to the same pressure as the pressure of the air space 16.Movable wall element 28 is, as a result, moved against the force of thebiasing means 32 and this, in turn, moves stem 26 thereby to open theprimary valve arrangement 18 (FIG. 2). The spool valve arrangement 60 inFIG. 3 is closed by adopting the position shown in FIG. 3 with thesealing ring 64 sealing the narrow passageway in which the spool element62 moves. The pressure chamber 30 is now sealed with respect to thecontrol mechanism 40 and the movable wall element 28 is thereforemaintained in the position shown in FIG. 2.

As the waste water is dispelled via the discharge tube 12 to the nozzle14, the pressure of the air in the air space 16 decreases and,therefore, the air pressure in the control mechanism 40 decreases. At apre-set low level, for instance about 3 bar, the adjustable non-returnvalve arrangement 54 in branch line 46 is set to open in order to permitthe higher pressure in the pressure chamber 30 to discharge. As thepressure in the pressure chamber 30 discharges, the movable wall element28 moves under the action of the spring 32 to reduce the volume of thechamber 30. This, via stem 64, causes the spool valve arrangement 60 toopen thereby enabling the pressure in the pressure chamber 30 to befully discharged through the non-return valve 58. This ensures that thepressure in the pressure chamber 30 and the control mechanism 40 arequickly equalised. Without the spool valve arrangement 60, it ispossible that the pressure in the pressure chamber 30 will only beallowed to discharge partially to the non-return valve 54.

The system is now ready for another cycle.

The circuitry in FIG. 4 may be used to detect leaks or blockages in thesystem. This can be done by monitoring the pressure in the system inorder to check that the pressure correctly rises and falls as itoperates. The pressure switch 74 can be operated by the water pressureat the pump or the pressure in the air supply side of the controlmechanism 10. The DC voltage of the DC supply 72 is modified tointermittent DC by the operation of the pressure switch 74. Thisintermittent DC can be passed through an electrical capacitor 76 to asensing circuit which operates the delay 78. If the sensing circuit doesnot receive a signal from the combination of the pressure switch 74 andcapacitor 76 according to a pre-set time, it switches of the water pumpwhich pumps waste water into the flexible bag 6 in the vessel 2 asdescribed.

FIG. 9 shows an alternative arrangement for the vessel to that shown inFIG. 1. Liquid for distribution enters the reservoir 202 in thedirection shown by arrow 200. This liquid may also have a small amountof air in it which is introduced via a controlled leak to improveefficiency and as a result, the flexible bag 6 can be reduced in sizeconsiderably so that the air space 16 is relatively small; the pressureof the air in the airspace 16 controls the valve control mechanism (notshown) in the direction indicated by arrow 201.

FIGS. 10 and 11 illustrate an alternative form of outlet arrangement 300comprising a circular chamber 301 having a tangential inlet 302 and aplurality of openings 303 in the base 304 of the chamber. Liquid underpressure is introduced into the chamber 301 via inlet 302 where it formsa vortex. Liquid then discharges under gravity through the relativelylarge (e.g. 1/2 to 1 inch in diameter) openings 303 which may each beconnected to hoses (not shown) for further distribution as required.

FIGS. 12 and 13 illustrate a self-propelled form of thewater-distribution apparatus shown generally in FIG. 1. The equipment800 comprises a chassis 801 having wheels 802 (two only shown), asteering arm 803 and a framework 804 which supports thewater-distribution apparatus 805. The water-distribution apparatus 805comprises a rigid outer housing 806 which is connected to a raingun 807(as described more fully above). At the rear of the equipment 800 thereis mounted a spool arrangement 810 which comprises two ground-engagingwheels 811 connected by a central spool member 812. The outer peripheryof the central spool member 812 is provided with a ratchet arrangement812a which interconnects, via a ratchet linkage 813, with a bellowsmotor 814. The bellows motor 814 is driven by the rise and fall (or thevariation) in the water-distribution housing 806. A pipeline 815delivering water for distribution is carried on the arm 803 and thechassis 801 to the rear of the equipment and the spool arrangement 810.The end of the pipeline 815 communicates with the water-distributionequipment via a line which is not shown but which links the centre ofthe spool member 812 with the water distribution equipment 805.

The spool arrangement 810 is connected via connecting arms 816 and 817to the chassis 801 and the frame work 804. Connecting arm 817 includesan adjustable spring 817a.

The ratchet linkage 813 enables reciprocating movement in the bellowsmotor 814 to be transformed into linear motion of the equipment 800along the ground. Thus, the linkage 813 comprises a lever 818 which isconnected to the bellows motor 814 about a pivot point 819. A rod 820 isconnected at one end to the lever 818 (which has an adjustable position)and

at the other end engages the ratchet 812a on the spool member.

The spool arrangement 810 may be lifted from the ground by operation ofa pivotable lever 821 which is connected to the spool arrangement 810 bythe connecting arm 817. Lever 821 includes an over-centre mechanism inorder to ensure that the spool arrangement 810 may be lifted from theground on operation of the lever 821.

In the working mode, the equipment 800 is moved forward by two means.Firstly, by tension at pipeline 815 and secondly by the contact of thespool arrangement 810 with the ground, since the outside of the wheels811 of the spool arrangement 810 will be rotating faster than the speedat which the pipe 815 is wound The adjustable spring 817a allows for anynecessary slippage. Thus, in use, the bellows motor 813 reciprocates andthe movement is transmitted via the lever 818, the rod 820 to drive theratchet on the spool member 812. In order to ensure that the pipe iswound evenly onto the spool 812, a roller 822 is provided which iscurved such that it is of a larger diameter on the inside than at itstwo ends (see FIG. 13) and this biases the pipe 815 to the outside ofthe spool 822.

For transporting equipment 800, the lever 821 is operated puttingtension on the connecting arm 817 and, via an over-centre mechanism,raising the spool mechanism 810 clear of the ground.

The forward wheel 802 of the equipment 800 is a castor wheel and issteered by the steering arm 803 which is guided by the pipeline 815which is held to the arm 803.

Employing the equipment of the present invention enables the waterdistribution apparatus to be drawn along the ground by the pipe which isdelivering liquid for distribution to the apparatus. This enables thewater to be spread over a much larger area than would be possiblewithout such a drive arrangement or mechanism.

I claim:
 1. A liquid delivery apparatus comprising(i) a liquid reservoirinto which a liquid may be introduced via an inlet to pressurize liquidin the reservoir; (ii) an outlet via which said liquid may be dischargedfrom the reservoir under the pressure of the liquid in the reservoir;(iii) a valve between the reservoir and the outlet to control passage ofliquid from the reservoir to the outlet, said valve having (a) anopening, (b) a closure member adapted to close the opening, and (c) abiasing means, the arrangement of the components of the valve being suchthat the valve is normally held closed under the force of the biasingmeans and the pressure of the liquid in the reservoir; (iv) a valvecontrol mechanism for controlling the operation of the valve in responseto the pressure of the liquid in the reservoir; and (v) a means fortransmitting the pressure in the reservoir to the valve controlmechanism; wherein the valve control mechanism comprises a movableelement which is capable of being acted on by the pressure of the liquidin the reservoir and transmitting a resultant force to the closuremember of the valve in a direction to open the valve, and wherein therespective effective surface areas of the movable element and theclosure member and the force of the biasing means are chosen such thatthe closure member is opened when the pressure of the liquid in thereservoir reaches a predetermined level.
 2. A liquid delivery apparatusaccording to claim 1, including a rigid housing and an inner movablewall which sub-divides the housing into first and second chambers whichare of variable volume depending upon the position of the said innermovable wall in the housing, the first chamber containing asubstantially compressible fluid and the second chamber defining saidliquid reservoir.
 3. A liquid delivery apparatus according to claim 2,wherein the inner movable wall is at least semi-rigid, with provision tomove in the housing to adjust the relative volumes of the first andsecond chambers.
 4. A liquid delivery apparatus according to claim 2,wherein the inner movable wall comprises a flexible membrane.
 5. Aliquid delivery apparatus according to claim 4, wherein the flexiblemembrane is a flexible bag.
 6. A liquid delivery apparatus according toclaim 2 wherein there is provided means for transmitting the pressure offluid in the first chamber to the valve control mechanism forcontrolling the operation of the valve.
 7. A liquid delivery apparatusaccording to claim 2 wherein the movable element of the valve controlmechanism is a wall element of a pressure chamber which chamber iscapable of being pressurized by the pressure of the liquid in thereservoir.
 8. A liquid delivery apparatus according to claim 7, furthercomprising a control arrangement between the first chamber and the valvecontrol mechanism to control the supply of pressure to the valve controlmechanism.
 9. A liquid delivery apparatus according to claim 8, whereinthe control arrangement includes a first means for adjusting thepressure of the fluid in the pressure chamber when the pressure in thefirst chamber is at a first predetermined level in order to move thewall element and transmit a force to the closure member to open thevalve, and a second means for adjusting the pressure of the fluid in thepressure chamber when the pressure in the first chamber is at a secondpredetermined level in order to permit the wall element to return to itsoriginal position and allow the valve to close.
 10. A liquid deliveryapparatus according to claim 1 further including a movable frame andincluding means for driving the frame in response to the oscillatingpressure of liquid in the liquid reservoir.
 11. A liquid deliveryapparatus as claimed in claim 10, wherein the oscillating pressure inthe liquid reservoir drives a bellows motor which, in turn, is coupledto a winch for moving the frame on which the delivery apparatus isaccommodated.
 12. A liquid delivery apparatus according to claim 1,wherein said outlet is movably mounted with respect to the reservoir andmeans are provided for causing the outlet to move, such that thedirection in which liquid discharged relative to the apparatus variable.13. A liquid delivery apparatus according to claim 12, wherein the saidoutlet is rotatably mounted on the apparatus.
 14. A liquid deliveryapparatus according to claim 12, wherein the means for causing theoutlet to move is mechanically actuated.
 15. A liquid delivery apparatusaccording to claim 12, wherein the means for causing the outlet to moveis actuated by the discharge of liquid from the reservoir underpressure.
 16. A liquid delivery apparatus according to claim 12, whereinthe means for causing the outlet to move is a striking member mounted onthe apparatus so as to be able to strike the outlet causing it to move.17. A liquid delivery apparatus according to claim 1, wherein the outletcomprises a chamber of circular cross-section having an inlet fordelivery of liquid from said reservoir and a plurality of openings fromwhich the liquid for distribution is dischargeable under gravity.
 18. Aliquid delivery apparatus according to claim 17, wherein said chamberinlet is tangentially disposed with respect to the chamber in order todissipate energy of incoming liquid.